This invention relates to a new process for heat and/or cold production by means of a cycle operated with carbon dioxide and a condensable fluid.
The prior art processes for cold and/or heat production by means of absorption cycles generally make use of the thermal effects occurring when absorbing and desorbing a solute in a solvent at distinct temperature levels which depend on the different operating pressures.
These processes require the use of pumps for circulating the solvent from a zone at a relatively low pressure to another zone at a higher pressure with the attendant known occurring such as possible degassing of the sucked or drawn solutions, or cavitation effects, so that substantial power consumption for this circulation and security is devices required to avoid the passage of high pressure fluid into the enclosures which are normally used at low pressure.
U.S. Pat. No. 4,311,019 illustrates, in its FIG. 1, the operation of a conventional absorption system, such as a conventionally used with usual associations by pairs such as water-ammonia or water-lithium bromide.
Absorption cycles have been modified by adding an inert gas whose object is to maintain a constant pressure in the different parts of the devices.
These installations, as described at page 744 of "Thermodynamique Technique" by M. Bailly, Bordas Editions, 1971, are usually employed for cold production, with, as a refrigeration agent, as an absorption agent and as an inert gas, respectively, ammonia, water and hydrogen. This poses security problems, particularly because ammonia toxicity and dangers resulting from hydrogen explosivity and ammonia flammability. The cycles using water as working fluid and a salt such as a lithium bromide have other disadvantages: very low operating pressure, i.e., possible icing and salt crystallization.
Another absorption cycle, described in U.S. Pat. No. 1,781,541, operates with the ammonia-water (NH.sub.3 -H.sub.2 O) association and an auxiliary condensable fluid such as butane. This cycle has been conceived for substantially isobaric working conditions of its different parts, the slight pressure variations being used to circulate the fluids in liquid or gas phase.
The device has however the major disadvantage of an uneven running since ammonia condensation can be avoided only with difficulty under the pressure and temperature conditions prevailing in the evaporator. The evaporation of butane then greatly decreases and the exothermic condensation of ammonia converts the evaporator to a heat source rather than a cold source.